Method and apparatus for sealing motor terminals

ABSTRACT

A wire insulator apparatus includes an insulator/separator member, a cap portion, a tube and potting material. The insulator/separator member has apertures formed therein for receiving a plurality of wires. By threading the wires through the insulator/separator member, the wires are spaced apart so that a potting material can be molded to provide a complete seal from the environment, particularly conductive liquids such as ammonia, which may cause short-circuiting between the wires. Individual wires are terminated in the cap portion, and the cap portion, the insulator/separator member and the wire ends are positioned within a tube or a mold portion depending on the application, and a potting epoxy is fluidly inserted within the tube. The epoxy surrounds or encases the wire ends within the tube or mold to insulate the wire ends in an airtight seal.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/709,274, entitled “METHOD AND APPARATUS FOR SEALING MOTOR TERMINALS,”filed Dec. 10, 2012, which claims the benefit of and priority to U.S.Provisional Application No. 61/570,397, filed Dec. 14, 2011, entitled“METHOD AND APPARATUS FOR SEALING MOTOR TERMINALS,” which are herebyincorporated by reference in their entirety.

BACKGROUND

The application generally relates to a method of sealing electric motorterminals. The application relates more specifically to a method andapparatus for sealing connections within a conductive environment.

Ammonia is a common, naturally occurring compound in the environmentthat breaks down naturally into hydrogen and nitrogen. Ammoniarefrigeration is a cost effective and energy efficient method ofprocessing and storing frozen and unfrozen foods. Ammonia refrigerationis also used in the chemical industry. Recently, air conditioning hasbeen provided by ammonia refrigeration systems in office buildings,parks, and small buildings such as convenience stores.

Ammonia is electrically conductive and corrosive to many materials,e.g., copper wire used in high efficiency electric motors. Electricalconnections, e.g., motor terminations of multiple conductors, which areexposed to ammonia in the environment, can present a risk of shortcircuit or other failure. Electrical conductors must be electricallyinsulated and sealed from ammonia vapor or liquid.

An example of a current motor connection arrangement is shown in FIG. 4.Lead wires 12 are soldered or crimped in a cap portion 28. The capportion is then inserted into a recessed stub portion 29 attached to oneend of a stud member 26. Stud member 26 may also include a hexagonal nutportion 27 to provide a surface for applying a wrench, for tighteningthreads on the stud member 26. An insulator board may be attached tostud member 26 for mounting stud member 26 to the compressor or motorhousing 116. The lead wire terminations 12 in cap portion 28 are notinsulated and would short circuit if exposed, e.g., to a conductive gasatmosphere or wet environment.

The innovation provides a method to make connections that electricallyinsulates the conductors while sealing out ammonia vapor or liquid.Currently the common process used for connecting electrical terminals insemi-hermetic compressors is stripping and soldering copper wires into acap, then inserting the cap into a stub and crimping the cap. There isno provision made for insulating the electrical terminals and conductingparts, as the conventional refrigerants are non-conducting and thus poseno risk of short-circuiting exposed terminals.

What is needed is a method and device for sealing motor terminals in asemi-hermetic compressor using a conductive refrigerant, e.g., ammonia.

Intended advantages of the disclosed systems and/or methods satisfy oneor more of these needs or provide other advantageous features. Otherfeatures and advantages will be made apparent from the presentspecification. The teachings disclosed extend to those embodiments thatfall within the scope of the claims, regardless of whether theyaccomplish one or more of the aforementioned needs.

SUMMARY

In one embodiment a wire insulator for sealing motor terminals includesan insulator/separator member, a cap portion, a tube and potting epoxy.The insulator/separator member includes a plurality of apertures. Theapertures are arranged for receiving and threading a plurality of wirestrands through the insulator/separator member. The plurality of wirestrands are separated to create a space for the potting epoxy to sealeach of the wire strands from an environmental atmosphere such asammonia. The cap portion is arranged to terminate the wire strands. Thetube is positioned surrounding the cap portion, the insulator/separatormember, the potting epoxy, and at least a portion of the plurality ofwire strands.

In another embodiment a wire insulator includes an insulator/separatormember, a cap portion, a hollow mold portion and potting epoxy. The moldportion encloses the insulator insulator/separator member, and the capportion, and a plurality of lead wire strands. The mold portion includesa first end and a second end. The mold portion is open at the first endand attached to an insulator board at the second end. The potting epoxyinfused into the mold portion to provide an airtight seal.

In a third embodiment a method for sealing wire terminations in aconductive atmosphere includes threading a plurality of lead wirestrands through a plurality of apertures in an insulator/separatormember, attaching the lead wire strands to cable conductors at aconnection point; placing a casing over the assembled connector parts;and filling the casing with an airtight electrically insulated pottingmaterial to encase the connector assembly in the potting material.

Certain advantages of the embodiments described herein include the useof copper wound motors in an ammonia refrigeration environment withinternal electrical connections made between two or more conductors.

Further, internal motor connections sealed from the refrigerant can bemade as well as pass-through connections. Connection free motor windingsand expensive multi-conductor pass-through devices are no longerrequired in the presence of ammonia.

The disclosure provides electrically insulated connections of multipleconductors in a semi-hermetic refrigeration compressor motor. Theinsulated connections are impervious to ammonia refrigerant vapor.

The application also discloses methods and devices to provide completelysealed electrical connections with separated conductors that are pottedto protect the copper or other electrical conductor materials.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an exemplary embodiment of a potted electrical connectiondevice.

FIGS. 2 and 2A show an alternate embodiment of a potted electricalconnection device.

FIG. 3 shows an exemplary embodiment of a method of sealing a motorterminal.

FIG. 4 shows an exemplary embodiment of a prior art motor terminalassembly.

FIG. 5 shows an exemplary semi-hermetic compressor having a pottedelectrical connection device.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to FIGS. 1 and 5, a semi-hermetic compressor 110 includes amotor 112 and a compressor portion 114. A semi-hermetic housing 116encases both compressor portion 114 and motor 112. Motor 112 includes astator 120 arranged about a magnetic core or rotor 118. Rotor 118 ismade of steel laminations that generate magnetic fields when motor 112is energized. When three phase AC power is applied, the magnetic fieldadvances from one stator winding to the next, causing the magnetic fieldto rotate and drive rotor 118. An electrical connection device orleadwire connector 10 is provided at one end of semi-hermetic compressor110 adjacent motor 112. In one embodiment, two or more lead wires orwire strands 12, e.g., conductors or motor windings from inside of motor112 or compressor housing 116, may be threaded through a cylindrical orsolid block insulator or casing 14. Insulator 14 has one or morepassages 16 traversing therethrough. Passages 16 have internal diametersufficient to accept lead wires 12. Passages 16 separate and insulatelead wires 12 from coming into contact with adjacent lead wires withininsulator 14. Lead wires 12 pass through insulator 14 and are connectedto a single lead wire or multi-conductor cable 18 at a connection point20. At connection point 20, lead wires 12 may be soldered, crimped, orotherwise attached to lead wire or multi-conductor cable 18. Lead wires12 are also threaded through a hollow insulating tube 22, preferably aheat-shrink tube.

Once the connection between lead wires 12 and lead wire/multi-conductorcable 18 is prepared, tube 22 is positioned over the entireassembly—insulator 14, lead wires 12 and the end portion of lead wire ormulti-conductor cable 18. Finally, tube 22 is filled with a pottingmaterial 24. Potting material may be, e.g., epoxy, urethane, silicone orother suitable potting material as known to those skilled in the art.The heat—shrink tube 22 is then heated to shrink the tube 22 over theconnection to be protected, e.g., using a hot air gun, oven or similarheating device. Tube 22 contracts, providing a snug fit over theirregularly shaped connection. Tube 22 provides, e.g., electricalinsulation, protection from dust, solvents and other foreign materials,as well as strain relief.

Referring next to FIGS. 2 and 2A, in an alternate embodiment, lead wires12, may be threaded through a cylindrical or solid block insulator 14.Insulator 14 has passages 16 traversing therethrough to accept leadwires 12. Passages 16 separate and insulate lead wires 12 from cominginto contact with adjacent lead wires within insulator. The mainfunction of item 14 is to separate the wires so that the pottingmaterial can provide a good seal. If the wires were kept together in abundle and covered in a potting material, there is a possibility that aleak path could occur between the wires because the potting material wasunable to fill all of the small voids between the wires. Lead wires 12pass through insulator 14 and are connected to a cap portion 28. Leadwires 12 are stripped of insulation 19 at the wire ends 17 to expose acopper or aluminum conductor for termination inside cap portion 28. Wireends 17 may be terminated within cap portion 28 by soldering, crimping,or other suitable means of making electrical terminations. Cap portion28 is then inserted into a recessed stub portion 29 attached to one endof a stud member 26. Stud member 26 may also include a hexagonal nutportion 27 to provide a surface for applying a wrench, for tighteningthreads on the stud member 26. An insulator board 25 may be attached tostud member 26 for mounting stud member 26 to the compressor or motorhousing 116.

A hollow mold portion or casing 15 is place over the insulator 14, leadwires 12, and cap portion 28. Mold portion 15 is open at the narrow end,and abuts against the insulator board 25 at the opposite, wider end. Aliquid potting material 24, e.g., epoxy may be infused into the hollowbore interior of mold portion 15, filling all of the voids within moldportion 15, and encasing the components therein—i.e., insulator 14, leadwires 12, and cap portion 28—in an airtight seal when the potting epoxycures.

In an alternate embodiment as shown in FIG. 2, lead wires 12 passthrough insulator 14. Lead wires 12 may be, e.g., Teflon-coated copperwires, aluminum wire, and other insulated coatings. Insulator 14separates individual wires 12 to permit epoxy or other potting material24 (FIG. 1) to flow around and between individual wires 12 and wire ends17 prior to curing, to provide insulation around all of the internalcomponents of the leadwire connector 10.

Referring next to FIG. 3, a method of sealing electric motor terminalsis disclosed. At step 100, the method proceeds by threading lead wires12 through insulator 14 to separate the lead wires 12. Next, at step102, lead wires 12 and the separate conductors in multiconductor cable18 are soldered or crimped at connection point 20. Following step 102,at step 104 tube 22 is then slipped over the assembly (including leadwires 12, conductors in multiconductor cable 18, connection point 20,insulator 14, and cap portion 28). Finally, at step 106, tube 22 isfilled with potting material 24 to embed the connector assembly in anelectrically insulated material and prevent the ammonia atmosphere fromcausing a short circuit.

It should be understood that the application is not limited to thedetails or methodology set forth in the following description orillustrated in the figures. It should also be understood that thephraseology and terminology employed herein is for the purpose ofdescription only and should not be regarded as limiting.

While the exemplary embodiments illustrated in the figures and describedherein are presently preferred, it should be understood that theseembodiments are offered by way of example only. Accordingly, the presentapplication is not limited to a particular embodiment, but extends tovarious modifications that nevertheless fall within the scope of theappended claims. The order or sequence of any processes or method stepsmay be varied or re-sequenced according to alternative embodiments.

It is important to note that the construction and arrangement of thesealed motor connector as shown in the various exemplary embodiments isillustrative only. Although only a few embodiments have been describedin detail in this disclosure, those who review this disclosure willreadily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter recited inthe claims. For example, elements shown as integrally formed may beconstructed of multiple parts or elements, the position of elements maybe reversed or otherwise varied, and the nature or number of discreteelements or positions may be altered or varied. Accordingly, all suchmodifications are intended to be included within the scope of thepresent application. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeembodiments. In the claims, any means-plus-function clause is intendedto cover the structures described herein as performing the recitedfunction and not only structural equivalents but also equivalentstructures. Other substitutions, modifications, changes and omissionsmay be made in the design, operating conditions and arrangement of theexemplary embodiments without departing from the scope of the presentapplication.

It should be noted that although the figures herein may show a specificorder of method steps, it is understood that the order of these stepsmay differ from what is depicted. Also two or more steps may beperformed concurrently or with partial concurrence.

1. A sealed wire insulator for sealing motor terminals of asemi-hermetic compressor in an electrically conductive environment, thesealed wire insulator comprising: an insulator/separator membercomprising a plurality of apertures, wherein the plurality of aperturesare configured to receive and thread a plurality of wire strands throughthe insulator/separator member, the plurality of wire strands extendsfrom a motor or compressor housing of the semi-hermetic compressor, theinsulator/separator member separates adjacent wire strands of theplurality of wire strands to create a space between the adjacent wirestrands; potting epoxy disposed in the space between the adjacent wirestrands, wherein the potting epoxy is configured to provide an air tightseal between each of the plurality of wire strands and the adjacent wirestrands and from the electrically conductive environment; and a hollowcasing surrounding the insulator/separator member, the potting epoxy,and at least a portion of the plurality of wire strands.
 2. The sealedwire insulator of claim 1, wherein the potting epoxy seals each of theplurality of wire strands from the electrically conductive environment,which comprises ammonia vapor or liquid.
 3. The sealed wire insulator ofclaim 1, wherein the hollow casing is a shrink tube.
 4. The sealed wireinsulator of claim 1, wherein the insulator/separator member iscylindrical.
 5. The sealed wire insulator of claim 1, wherein theinsulator/separator member is a solid block.
 6. The sealed wireinsulator of claim 1, wherein the hollow casing is a molded casing. 7.The sealed wire insulator of claim 1, wherein the hollow casingcomprises a narrow end and a wider end oppositely facing the narrow end.8. The sealed wire insulator of claim 7, wherein the plurality of wirestrands is terminated in a cap portion positioned proximate the widerend.
 9. The sealed wire insulator of claim 1, wherein the pottingmaterial is selected from epoxy, urethane, silicone, or other suitablepotting material having non-conductive properties.
 10. A sealed wireinsulator for sealing motor terminals of a semi-hermetic compressor inan environment comprising ammonia vapor or liquid, the sealed wireinsulator comprising: potting epoxy; an insulator/separator membercomprising a plurality of apertures, wherein the plurality of aperturesare configured to receive and thread a plurality of lead wires throughthe insulator/separator member, the plurality of lead wires extends froma motor or compressor housing of the semi-hermetic compressor, and theinsulator/separator member separates adjacent lead wires of theplurality of lead wires to create a space between the adjacent leadwires; a hollow casing surrounding the insulator/separator member, thepotting epoxy, and at least a portion of the plurality of lead wires,wherein the potting epoxy is infused into the hollow casing and fillsthe space between the adjacent lead wires and an additional spacebetween the adjacent lead wires and the hollow molded casing, whereinthe potting epoxy is configured to provide an air tight seal betweeneach of the plurality of lead wires and the adjacent lead wires and withthe environment.
 11. The sealed wire insulator of claim 10, wherein theplurality of lead wires comprises Teflon-coated copper wire strands. 12.The sealed wire insulator of claim 10, wherein the plurality of leadwires comprises aluminum wire strands.
 13. The sealed wire insulator ofclaim 10, wherein the plurality of lead wires comprises insulatedcoatings.
 14. The sealed wire insulator of claim 10, wherein the hollowcasing comprises a narrow end and a wider end oppositely facing thenarrow end.
 15. The sealed wire insulator of claim 14, wherein theplurality of lead wires is terminated in a cap portion positionedproximate the wider end.
 16. The sealed wire insulator of claim 10,wherein the insulator/separator member is cylindrical.
 17. The sealedwire insulator of claim 16, wherein the insulator/separator member is asolid block.
 18. The sealed wire insulator of claim 10, wherein thepotting material is selected from epoxy, urethane, silicone, or othersuitable potting material having non-conductive properties.
 19. A methodfor sealing wire terminations in a conductive atmosphere comprising:threading a plurality of lead wire strands through a plurality ofapertures in an insulator/separator member to form assembled connectorparts; attaching the plurality of lead wire strands to cable conductorsat a connection point; placing a casing over the assembled connectorparts to form a connector assembly; and filling the casing with anairtight electrically insulated potting material to encase the connectorassembly in the potting material.
 20. The method of claim 19, whereinthe casing is one of a tube or a molding.